In cut-off systems of the double cut type the tubing is clamped within a set of clamping jaws and a notching blade is reciprocated across the upper periphery of the tubing just prior to the descent of the main cut-off or shearing blade. This prenotching eliminates cusping or dimpling of the tubing, thus subsequent reshaping of the ends of the severed tubing is not required.
In order to notch the tubing, a notching blade mounted to a cross slide is pushed or pulled across the tubing periphery after the tubing is clamped to the die set prior to the descent of the shearing blade. Both push and pull across notching methods are known. See U.S. Pat. Nos. 4,108,029; 4,109,555 and 4,646,601.
In order to translate the vertical reciprocal motion of the upper and lower platens into a horizontal reciprocal motion of the cross slide, a cam, having a curvilinear cam track, is mounted to the upper platen and a cam follower is fixed to the cross slide assembly. As the ram of the cut-off press begins its downward stroke, the cam attached to the upper platen is also forced downward causing movement of the cam follower as it follows the curvilinear cam track. Movement of the cam follower causes the cross slide to complete the notching stroke. Once the tubing is severed by the shearing blade, the ram, operating in a reverse manner, raises the upper platen of the die set. Raising the upper platen causes the cam follower to follow the curvilinear cam track which returns the cross slide to its initial position in preparation for a new cutting cycle. Using the cam/cam follower assembly in this manner allows the reciprocating vertical motion of the platen to be translated into a reciprocating horizontal motion of the cross slide. Cross slide assemblies of this type are known. See U.S. Pat. No. 4,766,792.